How do you calculate RL?

– method to calculate RL; height of collimation (H of C) = reduced level( R.L. ) + backsight (B.S.) reduced level ( R.L. ) = height of collimation (H of C) – foresight (F.S.) reduced level ( R.L. )

What does RL mean in surveying?

Reduced level. From Wikipedia, the free encyclopedia. Relative level in surveying refers to equating elevations of survey points with reference to a common assumed datum.

Is RL the same as AHD?

These levels are referred to as “Reduced Levels” ( R.L. ) which means a height above (or below) a nominated datum. In Australia, this datum is called the “Australian Height Datum” ( A.H.D. ) and is the relative height of a point in relation to Australian mean sea level.

How do you take rl in a survey?


  1. Set up the leveling instrument at Level position 1.
  2. Hold the staff on the Datum ( RL +50 m) and take a reading.
  3. Move the staff to A and take a reading.
  4. Move the staff to B and take a reading.
  5. Move the staff to C and take a reading.
  6. Move the staff to D and take a reading.
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How do you calculate RL level?

9. 8 Rise and Fall Method This method consists in finding the difference of level between consecutive points by comparing each point after the first with that immediately preceding it. The reduced level ( R.L. ) is found by adding rise of subtracting fall to or from the preceding reduced level itself ( R.L. ).

How do you calculate RL from Rise and Fall?

Rise and Fall Method is the method of calculating the difference in elevation between consecutive points in levelling work. Arithmetic check:

  1. Last R.L – First R.L = 42.842 – 43.000 = -0.158 m.
  2. ∑B.S – ∑F.S = 7.561 – 7.719 = -0.158 m.
  3. ∑ Rise – ∑ Fall = 4.932 – 5.090 = -0.158 m.

What do RL mean?

Summary of Key Points

Definition: Real Life
Type: Abbreviation
Guessability: 2: Quite easy to guess
Typical Users: Adults and Teenagers

What is an RL height?

Reduced level ( RL ): this is the height or elevation above the point adopted as the site datum for the purpose of establishing levels. To establish the required depths for a drainage system you need to work from the datum point. The datum is taken as a reduced level of 10,000.

What is TBM level?

Temporary Bench Mark ( TBM ) – a point of known height above a pre-defined level. This level is not absolute and is defined locally by the surveyor for the purpose of the survey.

How do you calculate AHD levels?

If you look on the footpath of recent developments in the area you will often see a rivet in the footpath which is either a relative level or a AHD point. If you can find a AHD point, and its value, you can then take points from this back to your property to find your own AHD levels.

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Why RL is given?

Ringer’s lactate solution ( RL ), also known as sodium lactate solution and Hartmann’s solution, is a mixture of sodium chloride, sodium lactate, potassium chloride, and calcium chloride in water. It is used for replacing fluids and electrolytes in those who have low blood volume or low blood pressure.

How do you calculate RL by HI method?

Height of Instrument Method | Surveying and Levelling

  1. Height of the Instrument Method.
  2. Determine the RLs of various points if the reduced level ( RL ) of a point on which the first reading was taken is 136.440 gives the height of collimation method and applies the check.
  3. HL = RL + BS.
  4. Check.

How do you calculate backsight?

Measure a backsight on A (for example, BS = 1.89 m). Measure on C a foresight FS = 0.72 m. Calculate HI = BS + E(A) = 1.89 m + 100 m = 101.89 m. Find the elevation of turning point C as E(C ) = HI-FS = 101.89 m – 0.72 m = 101.17 m.

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